识别数据框中的元素

Question

我在 pandas 中有一个名为 names_and_places 的数据框字典，如下所示。

姓名和地点：

Alfred,,,

Date,F_1,F_2,Key

4/1/2020,1,4,NAN

4/2/2020,2,5,NAN

4/3/2020,3,6,"[USA,NY,NY, NY]"

Brett,,,

Date,F_1,F_2,Key

4/1/2020,202,404,NAN

4/2/2020,101,401,NAN

4/3/2020,102,403,"[USA,CT, Fairfield, Stamford] "

Claire,,,

Date,F_1,F_2,Key

4/1/2020,NAN,12,NAN

4/2/2020,NAN,45,NAN

4/3/2020,7,78,"[USA,CT, Fairfield, Darian] "

Dane,,,

Date,F_1,F_2,Key

4/1/2020,4,17,NAN

4/2/2020,5,18,NAN

4/3/2020,7,19,"[USA,CT, Bridgeport, New Haven] "

Edward,,,

Date,F_1,F_2,Key

4/1/2020,4,17,NAN

4/2/2020,5,18,NAN   

4/3/2020,7,19,"[USA,CT, Bridgeport, Milford] "

（上面的文字或下面的图片） 

Answer 1

这是一种更有效的方法。您首先从字典中构建一个数据框，然后在该数据框上执行实际工作。single_df = pd.concat([df.assign(name = k) for k, df in names_and_places.items()])single_df["Key"] = single_df.Key.replace("NAN", np.NaN)single_df.dropna(inplace=True)# Since the location is a string, we have to parse it. location_df = pd.DataFrame(single_df.Key.str.replace(r"[\[\]]", "").str.split(",", expand=True))location_df.columns = ["Country", "State", "County", "City"]single_df = pd.concat([single_df, location_df], axis=1)# this is where the actual query goes. single_df[(single_df.Country == "USA") & (single_df.State == "CT")].name输出是：2     Brett2    Claire2      Dane2    EdwardName: name, dtype: object